1. Field of the Invention
The invention relates in general to a multi-channel driving circuit and a driving method thereof, and more particularly to a multi-channel driving circuit capable of effectively reducing electromagnetic interference, and a driving method thereof.
2. Description of the Related Art
When a multi-channel driving circuit is needed in the system application to drive multiple post-stage loads, an instantaneously high driving current is usually formed such that a significant electromagnetic interference (EMI) is induced to the overall system. In order to prevent the multi-channel driving circuit from generating the instantaneously high current, a regular time interleaving delaying method is used to lower the instantaneously main peak current.
FIG. 1 (Prior Art) shows clocks in a conventional multi-channel driving circuit using a regular time interleaving delay method. As shown in FIG. 1, N driving signals correspond to N channels, and a delay time amount Δτ exists between two adjacent driving signals so that the corresponding to-be-driven elements are driven in different driving time.
Because the driving times are interleaved and all the post-stage to-be-driven elements are not driven simultaneously, it is possible to prevent the multi-channel driving circuit from outputting the instantaneously too-high main peak current. However, each driving signal is sequentially turned into the high level voltage, but this causes multiple high-order harmonic tones in the frequency domain. FIG. 2 (Prior Art) shows frequency spectra in the conventional multi-channel driving circuit using the regular time interleaving delay method. In FIG. 2, noise exists in the frequency doubling portion so that the signal-to-noise ratio (SNR) is deteriorated.